It really depends on whether you buy into the whole 'they were the greatest band ever thing'. It was written by someone in their inner sanctum. Of course it's going to be self indulgent. They all thought they were the best thing ever. I thought the focus on Jimmy Page's obsession with the occult and highlighting the strained relationship of page and plant after John bonhom's death was done relatively objectively considering. The whole book was never going to be an objective critique on the band so not sure why you dislike it. Do you like Led Zeppelin?

3/4 of it was about how deep and magical they were. Was very disappointing.

Speaking to my Dad who was a massive fan, it was a big part of their appeal at the time how dark they were. And how loud and obnoxious they were live. The idea of John Bohnom playin a 45 min drum solo in the middle of Moby Dick I found hilarious

I do like led zeppelin but I've read books on musicians of bands that I don't like that I've loved. The dirt being the best example of that. I just felt so many parts of it were skim worthy. Just not that well written and if a book is well written it shouldn't matter if you buy in to anything about them in the first place.